User Guide

Midas XL4 Automation system
Page 5
Introduction.
Automation system overview.
The MIDAS XL4 is an ‘intelligent’ live mixing console. It utilises microprocessor technology to
provide the operator with unprecedented features for a live console, whilst remaining easy to use and
retaining the familiar look of a normal console.
The update speed of the MIDAS XL4 automation was a high priority of the system design, the
entire console is capable of updating itself over fifty times a second. Thus the delay between pressing the
‘RECALL’ button and the desk update is negligible.
Some sound engineers harbour concerns about giving control of a sound system over to
computers, in the case of the MIDAS XL4 these concerns are unfounded. For one thing, the MIDAS XL4
is a ‘computer assisted’ console. Most of the audio functions may be controlled without the aid of
microprocessors, and aall audio functions may be controlled without the central control CPU.
With the exception of the central controller CPU, the microprocessor chips used are ‘single chip
micro’s’ or ‘microcontrollers’. The CPU, program memory, RAM, data converters and timers are all
housed in a single chip. This gives the utmost in reliability as the ‘computer’ itself is protected from the
outside world by it’s input/output ports.
Fifty microprocessors (in a standard 48 input console) split the workload, resulting in high speed
operation and also providing the large degree of protection required for live performances. Should one
microprocessor ‘fall over’ the others will continue to operate normally.
In addition, the system has been designed is such a way that if a microprocessor does fail, the
audio circuits controlled by that unit will usually remain active in the state last recalled. The chances of a
microprocessor failing in such a way as to reconfigure its audio control circuits are extremely remote. The
most likely indication that a microprocessor has failed will be that it fails to respond to the central control
CPU. The audio circuits will continue to work.
Important controls such as the MUTE switch, whilst they can be over-ridden by microprocessor
control, will work without the intervention of a microprocessor.
Each input channel has its own microprocessor, the VCA master section has one and the final
microprocessor is in the central control section.
All the microprocessors are located in the fader bay of the XL4. No audio passes through the fader
bay, allowing a high degree of immunity to digital breakthrough to be achieved.
The use of multiple processors also means that the software, instead of being one large program, is
broken up into a number of small programs which are easier to test and debug, minimising the chances of
software problems.